Basement membrane components, collagen and non-collagenous glycoproteins, can be isolated in a soluble form from murine and human tissues or cultured cells by methods not expected to chemically modify the isolated components. A glycoprotein component specific to epithelial basement membranes can be obtained from murine kidney or from the medium in which murine teratocarcinoma cells are grown by extraction with buffers. Characterization of these glycoproteins indicates common antigenic properties and amino acid compositions, but differences in sugar composition. These glycoproteins will be digested with nonspecific proteolytic enzymes, and the resultant small glycopeptides will be analyzed biochemically. Immunologically identifiable basement membrane glycoprotein isolated from human tissues will be biochemically characterized and compared. Basement membrane components of both human and murine origin will be recombined in order to study the mechanisms involved in the formation of the macromolecular complex which is morphologically identifiable as basement membrane. The mechanisms of synthesis of the oligosaccharide portion of epithelial basement membrane will be studied in an in vitro system in which murine teratocarcinoma cells will be grown in chemically defined medium. Under these conditions, the oligosaccharide chain is not synthesized. The approaches to this problem will include manipulation of the available monosaccharide pool, examination of the effects of vitamin A and assessment of the role of dolichols in the synthesis of the oligosaccharide.